Portions of the vasculature of a patient may be treated to prevent blood flow through a target blood vessel. Conditions for which vessel closure may be indicated include tumors, aneurysms, arteriovenous malformations, varicose veins, and others. In some examples, a vessel closure system may include a catheter for delivering an adhesive or a sclerosing agent to a treatment site within a target vessel. During treatment, a clinician may apply external pressure to the treatment site after delivering the adhesive, thereby causing the target vessel to collapse onto the adhesive. Some vessel closure systems may include coils, plugs, or other devices that may be placed within the target vessel to prevent blood flow, instead of or in addition to adhesives or sclerosing agents.